Candidate dwarf planet discovered beyond Pluto's orbit

The Vera C. Rubin Observatory, in Chile, has discovered a candidate dwarf planet beyond Pluto’s orbit, named 2026 ED138. The celestial body could have a diameter of up to 1,500 kilometers and was identified at approximately 6.9 billion kilometers from the Sun, a distance that places it in the most peripheral and least explored regions of the Solar System.

The discovery comes as part of the Legacy Survey of Space and Time observation campaign, which began on June 30 and had already led to the identification of more than 11,000 new asteroids, including approximately 380 trans-Neptunian objects: bodies that orbit beyond Neptune, in the same peripheral region of the Solar System where the new candidate dwarf planet is also located.

The number of trans-Neptunian objects already identified by the campaign — approximately 380 out of more than 11,000 total asteroids — gives a measure of the telescope’s ability to scan the most distant regions of the Solar System, where light reflected by celestial bodies is extremely faint and identifying them requires repeated observations over time. The Rubin Observatory, which became fully operational during the course of the year, was designed precisely to carry out systematic and repeated surveys of the entire sky visible from the southern hemisphere, a strategy that increases the chances of identifying faint and distant bodies like 2026 ED138 compared to the one-off observations conducted by previous telescopes.

Confirmation of 2026 ED138’s status as a dwarf planet will require further observations to precisely determine its shape, composition and complete orbit: at present the diameter estimate, up to 1,500 kilometers, remains a possible value and not a definitive one. Only the continuation of the LSST campaign, which will keep tracking the celestial body’s position in the coming weeks, will make it possible to narrow the range of uncertainty regarding its actual size and orbital trajectory.